Playing around with errors in Python - NameErrors
 Let's start with NameErrors,  which is one of the more common errors that a newcomer to Python will come across. It is reported when Python can't find a local or global variable in the code. One reason this might pop up is because a variable is being referred to outside of it's namespace . To give you an example    a =  10   def  test_f ():     a =  20      print  a  test_f() print  a    Let's walk through the code. After defining the variable a  and the function test_f, you would naively expect the test_f()  function call to change the value of a  to 20 and print 20. You expect the print  statement after the function call to also print 20. Because you expect the function call to have changed the value of a. But, if you try running the code for yourself, you'll notice that the final print  statement will print 10. This is where namespaces  come into the picture.   Now, let's try this instead    def  test_f ():     b =  20      print  b  test_f() print  b    The...